When this is implemented on the main game, will it be retroactive? For example, if I have 50,000,000 bits wagered over the lifetime of my account, will I automatically get 500,000 silver?
It will only be on the new game, otherwise there will be an insane silver-glut (and not to mention, bustabit current supports 0% house edge bets so it's often pretty easy to inflate your wagered amounts if you're careful)
Maybe the average house edge is being increased to 1% so the supply or silver matches that of valor?
Well derived

My current thinking is that the most straight-forward is just a flat 1% house edge on all bets. That's what's on the dev site right now (although I haven't yet provided methodology, so you can't really prove it). My current plans are to remove bonuses completely from the main game (and put that in a separate, much more pvp game with ~10% bonuses). I really hate to remove the bonuses and variable-house edge, but with the vast majority of bustabit players playing "bonus oblivious" I can't help but feel I'm doing them a disservice.
With the new system, the effective house edge will be ~0.5% no matter how you play. When players do well and win money, there will be a glut of valor on the market (and no new silver) so I expect the house edge will be rather closer to 1%. And when players lose money, there will be a glut of silver on the market (investors wanting to realize their profits) so the silver be worth more and the house edge will be closer to 0%.
Smart traders I imagine will want to take advantage of this and "time arbitrage" the value of silver and valor to ~0.5 bits.
My hope is it'll be a fun little ecosystem